Meltzer's fourth and final magic trick is transformation — changing one thing into something else. He uses the metaphor of a hall of mirrors: as kids, we see endless versions of ourselves in the reflections, all the possibilities. But as we get older, we lock into one version and stop evolving. He warns that writing things in stone makes everything hard, brittle, and dusty. He tells graduates to write in pencil and be unafraid to use the eraser. The person who thinks they're the smartest in the room, he promises, is not — that's just the one with the most fragile ego. True intelligence is the willingness to keep learning.